A method of treating osteoarthritic joints with polysiloxanes

ABSTRACT

Joints are treated for osteoarthritis and other conditions in both animals and human beings by injection of pure polysiloxane fluid (such as dimethylpolysiloxane, methylphenylpolysiloxane and fluoromethylpolysiloxane).

United States Patent Ongley [451 Oct. 10, 1972 1 A METHOD OF TREATING [56] References Cited OSTEQARTHRITIC JOINTS WITH UNITED STATES PATENTS POLYSILOXANES 2,846,458 8/1958 Haluska ..424/1 84 [72] Inventor: Milne Joseph o l 13 win 3,239,414 3/1966 Rowan et al ..424/184 Street, Wellington, New Zealand Pnmary Examiner-Albert T. Meyers Flledi y 1969 Assistant Examiner-Norman A. Drezin [21] Appl. No: 841,151 Att0mey0wen, Wickersham & Erickson [57] ABSTRACT US. J ints ar treated for steoarthritis and other condi- [51] Int. Cl. ..A6lk 27/00 tions in both animals and human beings by injection of [58] Field of Search ..424/l84; 167/65 p p y il x n fl i (such as dimethylpolysiloxane,

methylphenylpolysiloxane and fluoromethylpolysiloxane 4 Claims, N0 Drawings METHOD OF TREATING OSTEOARTHIRITIC JOINTS WITH POLYSILOXANES This invention relates to the treatment of joints for arthritic troubles such as osteoarthritis.

In the case of a weight bearing joint, particularly the hip joint, the physiological degeneration that often accompanies aging is characterized by loss of chondroitin sulfate and consequent loss of elasticity of the articular cartilage. Normally, when the femoral head. is in contact with the acetabulum during weight bearing, the labrium transmits pressure to the femoral head over a large area. Over this pressure area the articular cartilage is thickest and contains most chondroitin sulfate. The central and inferior surface of the femoral head is opposed to the central soft fat pad of the acetabulum, and the extreme outer margin of the head lies unopposed. Here where the pressure is least, cartilagenous degeneration occurs most rapidly. The process is apparently accelerated by inactivity and lack of pressure.

The degenerated cartilage is shed into the joint cavity and is engulfed by the synovial membrane. It disintegrates and is absorbed, meanwhile causing a chronic reactive hyperaemia in the synovium. Fibrosis of a progressive nature results, and the synovium thickens as does the subsynovial tissue and the overlying capsule. Adhesions obliterate the synovial space. The synovial fluid has by now disappeared. The process is most pronounced at the inferior region of the joint. When fibrosis has caused thickening, shortening and loss of elasticity of the inferior capsule, the femur is pulled into the characteristic abnormal position of flexion, adduction and external rotation. Severe stretching of the sensitive capsule results in pain. This process will result in deformity, limitation of motion and eventual crippling.

Many methods have been tried to restore function and to alleviate the pain. Operative procedures are many, but, on the whole, the result has been unsatisfactory. Conservative measures, in spite of repeated applications, have yielded no permanent improvement.

Normally, synovial fluid is present in the joint cavity to act as a lubricant for the bearing surfaces of the joint. Under the above-described and some other circumstances, the quantity of fluid within this cavity falls below the optimum required, so that the joint surfaces are starved of lubricant. The joint surfaces thus tend to bind and so give rise to osteo-arthritis. During normal usage of a synovial joint, the pounding action that takes place between the two portions of the joint squeezes nutrition from the spongy bone to feed the articular cartilage which lines the opposed ends of the bones of the joints. If because of an injury or for any other reason the joint is not used, or is not used to its fullest extent so that the pounding necessary for the supply of synovial fluid diminishes or ceases, then the production of synovial fluid likewise diminishes. This deterioration of the joint also occurs as a result of physiological ag- Synovial fluid consists of ordinary intercellular fluid in which is dissolved a highly polymerized mucin-hyaluronic acid. This mucin makes the fluid viscous and endows it with its lubricating properties.

In this invention, the synovial fluid is replaced with viscous synthetic lubricant. This substitute material has properties similar to those of the natural synovial fluid, but is different in other aspects. Whereas the synovial fluid, being aqueous, is in equilibrium with blood plasma, the replacement of this invention is insoluble and non-toxic. Like other prostheses, it is inert and non-toxic and, while it is not a solid, is sufficiently highly polymerized to be a very viscous liquid.

Three classes of substances may be used in this invention: alkylpolysiloxanes, alkylarylpolysiloxane, and fluoroalkylpolysiloxanes. As examples of suitable polysiloxanes, good results have been obtained from dimethylpolysiloxane in various viscosities, including, for example, Elicon No. l at 10,000 centistokes, and Dow Corning Fluid 200 at 50 centistokes and Medical Fluid 360 at 350 centistokes. Also, methylphenyl polysiloxane has been used, such as Dow Corning Fluid 555, having a viscosity of 20 centistokes. A typical fluorine-substituted polysiloxane that has been used is Dow Corning F. S. 1265, fluoromethylpolysiloxane having a viscosity of 1,000 centistokes.

The most appropriate viscosity may depend on the individual person or animal and on the joint concerned.

The material should be pure-free of silica and other adjuvants, for silicone antifoaming agents containing adjuvants have produced emboli.

Example l-Injection into the hip joints of rabbits In one set of experiments 5 ml of Dow Corning Fluid 200 in some instances and 5 ml of Dow Corning Fluid 555 in others were injected into the hip joints of rabbits which were subject to a disease involving general calcification, particularly of the heart and kidneys, which caused their death within a few weeks up to six months after the hip-joint injection. No bad effects were traceable to these injections, and the silicone was detectable in the joint after many weeks.

Example 2-Intraperitoneal injection of rabbits To test whether there would be bad side effects, four rabbits were injected intraperitoneally with 5 ml of Dow Corning F8. 1265. Although one rabbit died in an epidemic of nephritis four months later, the other three survived without ill effects for the full 6 months period of the experiment.

Example 3Injection into the bloodstream of sheep In order to test the possibility of bad side effects, it was decided to inject some Elicon No. 1 directly into the bloodstream. The necessity of using a relatively large gauge needle together with the difficulty of dislodging the silicone from the end of the needle in the vein led to the use of sheep rather than rabbits. The jugular vein of the sheep was chosen because of its size and ease of approach. It was exposed under local anaesthesia and the needle inserted. One sheep received 154 ml silicone in one lot while the other two received six and ten lots of 77 ml each respectively at one minute intervals, making a total of 0.462 and 0.77 liter. One sheep was killed after one month and showed no macroscopic or microscopic abnormality of lung, heart, kidney, liver or brain. The other two were still healthy one year later when the experiment was terminated. The sheep received an amount of silicone many times greater than would be inadvertently taken up from a treated joint.

Example 4--General clinical procedure for human patients Amounts of dimethylpolysiloxane varying according to the estimated joint space are injected into knee or hip joint using an Elicon screw syringe. The patient lies on the unaffected side with the lower hip fully flexed. The affected hip and knee are extended. The needle is thrust, at right angles to the shaft of the femur, into the hip joint which now lies about 1.25 cm above the greater trocanter.

Example 5A typical case history The following case history is typical of the many patients treated according to this invention.

A patient complained of pain and stiffness with associated loss of movement. These signs first appeared 15 years previously. During the last five years she had experienced discomfort in bed and marked stiffness and pain for the first few steps after sitting. When the pain was particularly severe, it spread down the front of the right thigh.

Examination revealed:

1. Atrophy of muscles of the thigh.

2. Complete loss of internal rotation.

3. Complete loss of extension.

4. A 40 loss of flexion.

5. A loss of external rotation.

6. All movements caused pain at their limits.

7. Transmitted stress as in suddenly stepping down caused a sharp pain in the right groin. Radiological examination showed marked arthritic changes with narrowing of the joint space.

An injection of 20 ml of dimethylpolysiloxane was made into the hip. This resulted in an immediate marked increase in the range of movements and the disappearance of pain from transmitted stress. With a little support the patient could run on the spot without pain. Exercises, especially to strengthen the psoas major, were prescribed.

When she was seen a month later, all stiffness had gone, her only complaint was of a sharp twinge in her groin on certain movements. On examination the joint was found to have an almost full range of movement, but there was still a marked weakness in the psoas major. To correct this, bicycle riding was prescribed and when she returned after another 6 weeks, the psoas was much stronger. She was now free of pain, had a full range of movement and could run freely. Passive forcing of hip joint movements caused only normal discomfort.

Discussion The replacement of diseased or excised joint components by newly formed functional tissue is essential for reversing the process of osteoarthritis. Many workers have shown that after operative procedures involving the smoothing of the roughened surfaces, the cambial cells of the periosteum are of particular importance as they are able to form cartilage as well as new bone. First hyaline cartilage is formed, later to be replaced by bone. The hyaline cartilage later forms a new articular surface. For this process to occur, the patient must be encouraged to engage in activity involving all the movements of the normal joint.

The introduction of dimethylpolysiloxane into the 10 joint cavity removes the causes of pain in osteoarthritis,

apparently by producing a smooth gliding surface, and it also allows a much increased movement of the joint. In turn, this reconstitutes the normal method of supplying nutritive materials to the articular cartilage. This method is not offered as a panacea for the treatment of osteoarthritis but it does offer an alternative to the operative and conservative treatments which are practised at the present time. None of these can claim to be a cure, nor in fact can it be predicted before treatment that there will be any permanent relief.

The method of this invention offers the patient an increase in movement with an accompanying decrease in pain and a reversal of the osteoarthritis process.

It will be apparent that the invention applies equally to joints that are original parts of the person or animal and to joints that are wholly or partially prosthetic, in living limbs.

It may also be noted that viscosities of the fluid may vary from 1 centistoke to 100,000 centistokes.

1 claim:

1. A method of treating osteoarthritic joints in human beings and animals, comprising the injection thereinto of an amount effective to produce a smooth gliding surface at the joint of prosthetic synovial fluid consisting of pure liquid polysiloxane having a viscosity between about 1 and about 100,000 centistokcs and chosen from the group consisting of dimethylpolysiloxane, methylphenylpolysiloxane, and fluoromethylpolysiloxane.

2. The method of claim 1 wherein said polysiloxane is dimethylpolysiloxane having a viscosity in the range of approximately 50 to 10,000 centistokes.

3. The method of claim 1 wherein said polysiloxane is methylphenylpolysiloxane having a viscosity of about 20 centistokes.

4. The method of claim 1 wherein said polysiloxane is fluoromethylpolysiloxane having a viscosity of about 1,000 centistokes.

* a a a a: 

2. The method of claim 1 wherein said polysiloxane is dimethylpolysiloxane having a viscosity in the range of approximately 50 to 10,000 centistokes.
 3. The method of claim 1 wherein said polysiloxane is methylphenylpolysiloxane having a viscosity of about 20 centistokes.
 4. The method of claim 1 wherein said polysiloxane is fluoromethylpolysiloxane having a viscosity of about 1,000 centistokes. 